Many activities that leverage the Internet involve communicating and sharing messages (a.k.a., sending messages). Multiple communications programs may be used to send messages over the Internet. For example, separate applications exist for sending e-mail messages, instant messages, digital pictures, and electronic calendar information. These different applications may be used to send messages to common people or common groups of people. However, conventionally, each application typically stores a separate list of people or groups of people with whom communication using that application regularly occurs. For example, an e-mail application has an address book, and an instant messaging application has a buddy list.